Effect of sediment properties on incipient motion of large solitary particles on fixed bed

Gogus M., Haspolat E.

PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-WATER MANAGEMENT, no.4, pp.161-171, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2021
  • Doi Number: 10.1680/jwama.20.00071
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), Communication Abstracts, Compendex, Environment Index, Geobase, ICONDA Bibliographic, INSPEC, Metadex, Pollution Abstracts, Civil Engineering Abstracts
  • Page Numbers: pp.161-171
  • Keywords: hydraulics & hydrodynamics, river engineering, sewers & drains
  • Middle East Technical University Affiliated: Yes


The effect of sediment properties such as shape, size, specific weight and packing (support) condition on the incipient motion of large solitary particles was systematically investigated. A series of experiments was conducted in a rectangular tilting flume with a smooth fixed (rigid) bed under uniform flow conditions. In each experiment, a thin fibreglass rectangular rod of height 1/5 or 1.5/5 of the height of the particle was placed just downstream of the particle to imitate the interaction of particles in rivers. Contrary to common belief and knowledge, it was found that the Shields parameter decreased as the dimensionless grain diameter increased for a given bed slope under rough turbulent flow conditions. Moreover, a larger shear stress was needed to start the motion of particles on steeper slopes for a given particle diameter. An increase in the ratio of the support height to particle height by 50% resulted in an increase in the dimensionless critical shear stress by almost six times for the same particle and relative roughness.